UCSC professor authors tumor sorting system

SANTA CRUZ &GT;&GT; Doctors may treat tumors differently, thanks to a new classification system resulting from a study led by UC Santa Cruz professor Josh Stuart.

Instead of ordering tumors solely by their body part origin, the system accounts for molecular characteristics such as genetic makeup and protein levels. Published Thursday in the medical journal Cell, the study is the result of a two-year Pan-Cancer Initiative, sampling tumors from more than 3,500 cancer patients at 16 U.S. institutions.

For 90 percent of the tumors, tissue-of-origin was the key defining factor. But the rest, said Stuart, showed other characteristics that led to a new classification. This new map of cancer may lead to different treatment options for that 10 percent, he said.

"More than anything, this study helps us tease apart what aspects of the tumor are due to the tissue versus what aspects are due to what we are calling the 'cell of origin,'" Stuart said.

For example, bladder cancer showed three main tumor types, one of which invaded the bladder's squamous cells. Squamous cells form a layer of flat, squishy cells found throughout the body. Unlike other bladder tumors, these squamous tumors showed similarities with head and neck tumors and have a worse prognosis.

With this information, doctors may choose to treat patients with squamous bladder tumors differently than other bladder cancer patients, Stuart said.

The enormous amount of data collected by the study is available online at www.synapse.org, for researchers to analyze in new ways and contribute findings, he said.

The study looks at 12 cancer types. The initiative's next analysis, set for release this fall, looks at 21 types.

The ultimate goal, said Stuart, is to use molecular data to understand how tumors move through the body.

"That's ultimately what kills the person, not the primary tumor, that mass, but it spreads and we don't know why it spreads and where it goes," Stuart said.

Cancer can be understood as faulty programming, said Stuart, a biomolecular engineering professor. Cells develop along a pathway, from stem cells to specific tissue cells. When cells are damaged along the pathway, they sometimes become the wrong type and continue to multiply.

For example, breast cancer cells may turn on a program only used in brain cells, giving it neuron-like characteristics that allow it to spread to the brain, said Stuart.

"But we don't know at this point if this is true. We need a new map for metastatic disease to add to the current map of primary tumors to help us gain insights," he said.

The study is part of a $100 million federally funded consortium called The Cancer Genome Atlas, founded in 2006. The consortium's goal is to catalog genetic mutations responsible for cancer.